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Full text of "A History of the Personal Computer"

Appendix A: Some Technical Details of Various 
Personal Computers 

Apple 

Apple II The computer used a MOS 6502 microprocessor 
operating at 1 MHz with 8K bytes of ROM and 4K bytes of 
dynamic RAM, expandable to 48K. The integral video 
system could display 24 rows of 40 characters in upper 
case only. Each character was a 5 by 7 dot matrix. The 
display also had a graphics mode with high and low 
resolutions. In low resolution the 40 horizontal by 48 
vertical locations could be in one of 15 colors. In high 
resolution the screen could display a maximum of 280 
horizontal by 192 vertical positions in 4 colors. The 
video system also included a mixed mode in both low and 
high resolutions, with graphics and four lines of text 
at the bottom of the screen. 

Apple lie The computer used a 65C02 microprocessor 
operating at 1.023 MHz with 16K bytes of ROM and 128K 
bytes of RAM. The unit had one 5.25-inch 140K byte Alps 
floppy disk drive. The monitor could display 2 4 lines of 
40 or 80-column text. The video system also had three 
graphic modes. The low-resolution mode had 40 horizontal 
by 48 vertical pixels in 16 colors. The high-resolution 
mode had 280 horizontal by 192 vertical pixels in 6 
colors. Then a double-high-resolution mode had 560 
horizontal by 192 vertical pixels in 16 colors. The 
single 5.25-inch Alps half-height floppy disk drive was 
built-in. The disk controller was the IWM (Integrated 
Woz Machine) chip as used on the Macintosh computer. The 
disks were single-sided with 35-tracks and 16-sectors. 
Apple lie The computer used a MOS 6502A 
microprocessor operating at 1 MHz with 16K bytes of ROM 
and 64K bytes of RAM, expandable to 128K. The storage 
system supported six 140K byte 5.25-inch floppy disk 
drives. The terminal could display 24 lines of 40-column 
text in both uppercase and lowercase characters. Each 
character was a 5 by 7 dot matrix. The computer had two 
standard graphic modes. A low-resolution mode produced 
40 horizontal by 48 vertical pixels with 16 colors. The 



AA/1 



AA/2 A History of the Personal Computer 

standard high-resolution mode produced 280 horizontal by 
192 vertical pixels with 6 colors. The video system 
retained the Apple II mixed mode in both low and high 
resolutions, with graphics and four lines of text at the 
bottom of the screen. Seven slots were available for 
peripheral boards. The unit included an additional 60- 
pin auxiliary slot on the motherboard that provided for 
one of two optional cards. 

The two optional cards could either display 80 
columns of text or both 80 columns of text display and 
an extension of memory to 12 8K bytes. The extended 
memory 8 0-column option card and suitable software 
enabled double-density graphics in both low and high- 
resolution modes . 

Apple IIGS The computer used a Western Design Center 
W65C816 microprocessor operating at 2.8 MHz with 128K 
bytes of ROM and 256K bytes of RAM, expandable to 8 
megabytes. The microprocessor had a 24-bit address bus 
and an 8-bit data bus. The unit had two operating modes: 
a native mode of 2.8 MHz and an Apple lie emulation mode 
of 1.02 MHz. The storage system included support for 
both 3.5-inch 800K byte and 5.25-inch 140K byte floppy 
disk drives. The terminal could display: 24 lines of 40 
or 8 0-column text. Graphic modes varied from low- 
resolution with 40 horizontal by 48 vertical pixels in 
16 colors, to super-high-resolution with 640 horizontal 
by 200 vertical pixels in 4 colors. An Ensonig digital 
synthesizer chip with 64K bytes of dedicated RAM 
provided new sound capabilities. The unit had a 44-pin 
memory expansion slot and seven 50-pin slots for 
peripherals . 

Apple III The computer used a Synertek 6502A 
microprocessor operating at 2 MHz with 96K bytes of 
memory, expandable to 12 8K. The unit included one built- 
in 5.25-inch, 143K byte floppy-disk drive. The terminal 
could display 24 lines of 80-column text. Graphic modes 
were 560 horizontal by 192 vertical pixels in monochrome 
and 280 horizontal by 192 vertical pixels in 16 colors 
or 16 shades of gray. The computer had four slots for 
peripheral cards that had certain compatibility with 
Apple II cards. An aluminum chassis acted as a radio 
freguency shield and as a heat sink that eliminated the 



Appendix A AA/3 

need for a cooling fan. Three additional disk drives 
could be daisy-chained from a rear connector. The Apple 
III floppy-disks had a new 16-sector format (compared 
with a 13-sector format on the Apple II) . 

Lisa The computer used a Motorola MC68000 
microprocessor operating at 5 MHz with 1 megabyte of 
RAM. The storage system had two Twiggy 5.25-inch 860K 
byte floppy disk drives and a separate 5 megabyte 
Winchester-type hard disk named ProFile. The display was 
a 12-inch monochrome monitor with a resolution of 720 by 
364 pixels. The computer used four additional 
microprocessors. Two from National Semiconductor 
controlled the keyboard and mouse, a 6504 controlled the 
two floppy disk drives and the hard disk controller had 
a Z-8. The floppy disk drives maintained a constant data 
density between the outer and inner tracks. 
Macintosh The computer used a Motorola MC68000 
microprocessor operating at 7.83 MHz with 64K bytes of 
ROM and 128K bytes of RAM. The storage system had one 
integral 3.5-inch 400K byte floppy disk drive from Sony. 
The 3.5-inch disks were single-sided with 80 tracks. The 
storage system recorded data at a constant rate similar 
to the Lisa Twiggy drive. A connector provided for an 
optional second external 3.5-inch floppy disk drive. The 
display was a 9-inch monochrome monitor with a 
resolution of 512 horizontal by 342 vertical sguare 
pixels. There were no expansion slots, but two high- 
speed serial ports provided for connection of 
peripherals. The separate keyboard had 58 keys (59 in 
the international version) , but no function or cursor 
keys . 

Macintosh II The computer used a Motorola MC68020 
microprocessor operating at 16 MHz with a floating-point 
coprocessor and one megabyte of RAM, expandable to 8 MB. 
The unit had an open NuBus architecture developed at MIT 
with six slots for plug- in boards. The 13-inch color or 
12-inch monochrome monitor could display 640 by 400 
pixels as compared to the 512 by 342 pixel display on 
the previous Macintosh computers. The display system 
could have either 16 or 256 colors or shades of gray. 



AA/4 A History of the Personal Computer 

Macintosh Portable The computer used a Motorola 
CMOS 68000 microprocessor operating at 16 MHz with 1 
megabyte of RAM expandable to 2 megabytes. The unit 
included a built-in 3.5-inch 1.4 megabyte floppy-disk 
drive. The portable had an Active Matrix Liguid Crystal 
Display with a screen resolution of 640 by 400 pixels. 

The computer was 15.25 inches wide by 14.83 inches 
deep and the height varied from 2 to 4 inches, front to 
back. The weight without a hard disk drive was 13.75 
pounds . The keyboard had 63 keys with a unigue 
arrangement for locating either a trackball pointing 
device or an 18-key numeric keypad on the left or right 
hand side of the keyboard. The computer used lead acid 
batteries with a power management system controlled by a 
6502 microprocessor. This provided 8 to 10 hours of 
operation on a single battery charge. 

Atari 

The Atari 400 computer used a MOS 6502 
microprocessor operating at 1.8 MHz with 8K bytes of 
RAM, expandable to 16K. The display had 16 lines of 32 
characters and a high-resolution mode of 320 by 192 
pixels . 

Commodore 

PET 2001 The PET 2001 computer used a MOS 6502 
microprocessor, had 14K bytes of ROM and 4K bytes of 
RAM, expandable to 8K. The 9-inch black and white CRT 
could display 25 lines of 40 characters and the 73-key 
keyboard included a numeric keypad. 

PET 4000 The PET 4000 computer used a MOS 6502 
microprocessor, had 18K bytes of ROM and 16K bytes of 
RAM, expandable to 32K. The configuration included a 12- 
inch green-phosphor display with a capability of showing 
25 lines of 40 characters. 

Cromemco 

Z— 1 The Cromemco Z-l computer used a Zilog Z-80 
microprocessor and had 8K bytes of memory. 

Z— 2 The Cromemco Z-2 computer used the S-100 Bus with 
21 slots for plug- in boards. 



Appendix A AA/5 

CTC Datapoint 

The CTC Datapoint 2200 computer terminal used a 
bit-serial processor in TTL logic with shift register 
memory. The terminal had a keyboard, 12-line screen 
display and two cassette tape drives. 

Digital Group 

The Digital Computer System was available with 
either an AMD 8080A, MOS 6502, Mostek 6800 or Zilog Z-80 
microprocessor. The processor board had 2K bytes of RAM. 
An input/output board and a video interface board that 
provided a 16 line by 32 character display were part of 
the system. An optional 8K static RAM board was 
available to increase the memory capacity. 

EPD 

The System One computer kit had 82 integrated 
circuits, IK bytes of memory, expandable to 8K and used 
57 instructions. 

HAL 

The HAL-4096, was a home-built 16-bit computer 
with 16 registers and 4K bytes of magnetic core memory 
from a surplus IBM 1620. 

Heath 

H8 The H8 computer used an Intel 8080 microprocessor, 
had IK bytes of ROM and memory cards were available in 
4K-byte increments to 32K. It had a unigue 50-pin bus 
for expansion cards. 

Hll The Hll computer used a DEC LSI-11 microcomputer 
board and had a 4K by 16-bit word memory that could 
accommodate up to 20K words. 

Heath/Zenith-89 The Heath/Zenith-89 computer used a 
Zilog Z-80 microprocessor operating at 2.048 MHz and had 
16K bytes of RAM, expandable to 48K. The 12-inch screen 
could display 24 lines of 80 characters. The keyboard 
subsystem and video display used an additional Z-80 
microprocessor . 

Accessories The H9 video terminal had a 67-key keyboard 
and the 12-inch CRT could display 12 lines of 80 
characters . 



AA/6 A History of the Personal Computer 



Hewlett-Packard 

The HP 9831A desktop computer used a HP BPC 

microprocessor and had 8K bytes of memory, expandable to 

32K. The unit had a 32-character LED display, cassette 

tape drive and a keyboard. 

Hyperion 

The Hyperion portable computer had an Intel 8088 
microprocessor and 256K bytes of RAM. The storage system 
had two 5.25-inch 320K byte double-density dual-sided 
floppy-disk drives. The unit had a 7-inch amber-on-gray 
monitor that could display 25 lines of 80 characters. 
The 28 pound portable unit included an integrated 
display, two floppy-disk drives and a detachable 
keyboard. The operating system was MS-DOS and the unit 
was priced at $4,950 (Canadian) . 

IBM 

5100 The 5100 portable computer had a built-in 
keyboard, monitor and magnetic tape cartridge storage 
system. The unit used an IBM developed microprocessor 
and memory consisted of 48K bytes of ROM and 16K bytes 
of RAM, expandable to 64K. The monitor could display 16 
lines of 64 characters. 

Scamp The Scamp computer used an IBM Palm 
microcontroller and had 64K bytes of RAM. The unit had 
an integrated keyboard and a small CRT that could 
display 16 rows of 64 columns. 

System/3 Model 6 This BASIC computer system used 
monolithic circuit technology and had 8K bytes of 
silicon chip memory, expandable to 16K. The design 
included a keyboard for direct data input, a 14-inch 
diameter disk storage drive with capacities of 2.5 to 
9.8 megabytes and a printer. The CRT could display 15 
lines of 64 characters. 



Appendix A AA/7 

IMSAI 

The IMSAI 8080 computer used the Intel 8080A 
microprocessor and included 4K bytes of memory. It also 
had a heavy duty power supply, commercial-grade paddle 
switches on the front panel and a six-slot S-100 Bus 
motherboard, expandable to 22 slots. 

Kenbak-1 

The Kenbak-1 computer incorporated small and 
medium-scale integrated circuits with a memory capacity 
of 256 bytes. It had three programming registers, five 
addressing modes and very limited input/output 
capabilities . 

Mark-8 

The Mark-8 computer used an Intel 8008 
microprocessor, had 256 bytes of memory, expandable to 
16K bytes by adding memory boards. The unit had 
provision for six circuit board modules. 

MITS 

The Altair 8800 computer used an Intel 8080 
microprocessor and had 256 bytes of memory. The Altair 
cabinet had space for eighteen cards . The basic unit had 
two slots, one for the CPU card and one for the 25 6 byte 
memory card. 

MOS 

The KIM-1 computer used a MOS 6502 microprocessor, 
had 2K bytes of ROM that contained the system executive, 
and IK bytes of PAM. The unit included an audio cassette 
interface, a 23-key keypad and a six-digit LED display. 

North Star 

The Horizon-1 computer used a Zilog Z-80 
microprocessor and had 16K bytes of RAM. It also 
included one or two 5.25-inch floppy disk drives and a 
12-slot S-100 Bus motherboard. 



AA/8 A History of the Personal Computer 

Noval 

The Noval 7 60 computer used an Intel 8 08 0A 

microprocessor, had 3K bytes of ROM and 16K bytes of 
RAM. 

NRI 

The NRI 832 kit had 52 integrated circuits, 32 
bytes of memory, used 15 instructions. 

Ohio Scientific 

The OSI 400 computer used either a Motorola 
MC6800, MOS 6501 or 6502 microprocessor. The unit had 
512 bytes of ROM and up to IK bytes of programmable 
memory was available. The board was designed for use 
with a 48-line expansion bus system. 

PolyMorphic 

Poly 88 The Poly-8 8 computer used an Intel 

8080 microprocessor, had 512 bytes of RAM and IK bytes 
of ROM. It also used the S-100 Bus with four slots, had 
a cassette interface 

System 8813 The System 8813 computer used an Intel 8080 
microprocessor and the video could display 16 lines of 
64 characters. The main unit could accommodate from one 
to three floppy-disk drives with 90K capacity each. 

Processor Technology 

Sol-10 The Sol-10 Terminal Computer used an 

Intel 8080A microprocessor and had IK bytes of PROM, IK 
bytes of RAM and IK bytes of video RAM. The computer 
could generate a 16-line by 64-character video display. 
The unit had a built-in 85-key keyboard and one slot for 
a S-100 Bus board. 

Sol— 20 The Sol-20 computer used an Intel 

8080 microprocessor, had IK bytes of ROM, 8K bytes of 
RAM and IK bytes of video RAM. It also had a heavier- 
duty power supply and five S-100 Bus expansion slots 



Appendix A AA/9 

REE 

The Micral computer used an Intel 8008 
microprocessor and included 256 bytes of RAM, expandable 
to one kilobyte. The system used a 60-bit data bus 
called Pluribus . 

Scelbi 

The Scelbi-8H computer used an Intel 8008 
microprocessor with up to 4K bytes of memory. The 
Scelbi-8B business computer had up to 16K bytes of 
memory. 

Sphere 

Sphere produced three computer models that used 
the Motorola MC6800 microprocessor; the Hobbyist, 
Intelligent and BASIC. The Hobbyist had 4K bytes of 
memory and a keyboard, the Intelligent had more features 
and the Basic had 20K bytes of memory and full extended 
BASIC software. 

SwTPC 

The SwTPC 68 00 Computer System used a Motorola 
MC6800 microprocessor, had 2K bytes of memory, 
expandable to 16K. A IK byte ROM chip contained the 
mini-operating system. The unit also contained an SS-50 
bus for eight interface boards . 

Tandy/Radio Shack 

TRS-80 The TRS-80 computer used a Zilog Z-80 
microprocessor, had 4K bytes of ROM and 4K bytes of RAM, 
expandable to 62K. The system included a separate 
cassette tape recorder and a 12-inch black and white 
monitor that could display 16 lines of 64 characters. 

A Disk System Expansion Unit had a disk controller 
which could support up to four drives . The diskette had 
a capacity of 83K bytes (formatted) with 35 tracks of 
2,500 bytes per track divided into ten sectors. 

Texas Instruments 

The TI-99/4 computer used a TI TMS9900 
microprocessor and had 16K bytes of RAM. 



AA/10 A History of the Personal Computer 

Xerox 

Alto The Alto computer system had a processor/disk 
storage cabinet, graphics display unit, keyboard and a 
mouse. The processor unit had a 16-bit custom-made 
processor similar to the Data General Nova 1220. The 
operating speed was 400,000 instructions per second. 
Memory incorporated an address space of 64K 16-bit 
words, expandable to 256K. The processor/disk storage 
cabinet had two 3-megabyte hard-disk drives. The 
graphics unit featured an 8 inch horizontal by 10 inch 
vertical black and white display. It used a bit-mapped 
raster scan with a resolution of 606 pixels horizontally 
by 808 pixels vertically that could display 60 lines of 
90 characters. The computer used a detachable keyboard 
supplemented by a mouse incorporating three buttons for 
program control.